47 



EXPLA NATION OF TERMS. 



Cymose. Of the nature of a cyme. Comp. 

 racemose. 



Cymose umbel. Cymose monopodial 

 inflorescence in which three or more 

 equally strong branches of limited growth 

 arise in a whorl from the primary axis 

 a short distance below its apex, and from 

 each of them in turn arises a like whorl 

 of branches and the process is repeated. 



Cystidium. In Hymenomycetes : large 

 unicellular spherical or ovoid body pro- 

 jecting beyond the basidia and para- 

 physes of the hymeniuni. 



Cystocarp. In Rhodophyceae : same as 

 sporocarp. 



Deeurrent. Running down into another 

 structure. 



D6doublement. Same as chorisis. 



Definite, {a) Of inflorescence : same as 

 cymose. (b) Of stamens : not more than 

 twenty in a flower. Comp. indefinite. 



Dehiscent. Opening at one or more fixed 

 points to allow contents to escape. 

 Comp. indehiscent. 



Dermal tissue. Tissue of the epidermis. 



Dermatogen. Primordial meristematic 

 epidermis of a growing point. 



Diagonal plane. Of a flower : any vertical 

 plane which is not antero-posterior or 

 lateral. 



Dialypetalous. Same as polypetalous. 



Dialysepalous. Same as polysepalous. 



Diaphragm, (a) In Characeae : con- 

 striction in the neck of nucule due to 

 inward projections of the segments of the 

 neck, {b) In Equisetum: transverse 

 septum in the nodes of stem. (<r) In 

 Heterosporous \'ascular Cryptogams: 

 layer separating the prothallium from 

 cavity of macrospore. 



Dichasium. Cymose monopodial inflor- 

 escence in which a pair of opposite equally 

 strong branches of limited growth arise 

 from the primary axis a short distance 

 below its apex, and from each of these in 

 turn arises a pair of like branches, and the 

 process is repeated. Same as false 

 dichotomy. 



Dichogamy. Asynchronous maturity of 

 the two kinds of sporophyll in a herma- 

 phrodite flower. Comp. homogamy. 



Dichotomy. Forking in pairs, i. e. cessation 

 of pre\ious increase in length at an apex 

 with continuation equally in two diverging 

 directions. Comp. monopodium. 



Diclinous. Same as unisexual. Comp. 

 monoclinous. 



Didynamous. An androecium of four sta- 

 mens in two pairs, one pair being longer 

 than the other, is termed didynamous. 



Dimorphism. In flower : heterogony with 

 two forms, one with anthers higher than 



stigma (short styled), the other with 

 stigma higher than anthers (long styled). 



Dioeciotis. Having male and female 

 organs on different individuals. Comp. 

 monoecious. 



Diplostemonous. An androecium is di- 

 plostemonous when stamens are in two 

 whorls, those of the outer whorl being 

 opposite to the sepals and alternating 

 with the petals (antisepalous or calycine), 

 those of the inner whorl being opposite to 

 the petals and alternating with the sepals 

 (antipetalous or corolline). Comp. obdi- 

 plostemonous. 



Discoearp. In Ascomycetes: same as 

 apotheciuni. 



Disk. Term of varying signification. In 

 this book used in special sense of an out- 

 growth of torus between androecium and 

 gynaeceum, usually nectariferous. 



Dissepiment. Partition in a fruit. 



Dorsiventral. Having a dorsal surface 

 and a ventral surface. Comp. radial. 



Doubling. Same as chorisis. 



Drupe. Fleshy fruit with more or less 

 indurated endocarp forming a single stone 

 (putamen). 



Dviplication. Same as chorisis. 



Dwarf-male. In Oedogonieae : a small 

 short-lived plant of few cells developed 

 from a zoospore (androspore) in the vi- 

 cinity of the oogonium and producing 

 spermatozoids. 



Egg-apparatus. Oosphere (ovum) and 

 the two synergidae at the top of embryo- 

 sac of ovule. 



Elaters. (a) In Hepaticae : sterile fusi- 

 form cells with spiral wall-thickening 

 which loosen the spore-masses in the spore- 

 capsule at the time of scattering of spores. 

 {b) In Equisetaceae : four club-like very 

 hygroscopic membranous bands attach- 

 ed at one point to a spore, formed by the 

 splitting of an outer coat of the spore, and 

 serving to keep the spores united in small 

 groups as they leave the sporangium. 



Embryo-sac. The macrospore in the 

 nucellus of an ovule (macrosporangium). 



Empirical diagram. Floral diagram 

 representing the relative number and 

 position of parts in any flower as they are 

 found at once by examination of the 

 flower. 



Endocarp. Innermost layer of a pericarp. 



Endochrome. In Diatomaceae : portions 

 of the cell-contents coloured brown by 

 diatomin. 



Endodermis. Single layer of cells un- 

 interruptedly connected laterally and 

 with longitudinal undulation of the radial 

 lateral walls, separating parenchymatous 

 tissues from dissimilar systems of tissue 



